For those that use them, what solar charger/powerbanks are you using? Any good or bad experiences with them?

I just received my first "nice" solar charger. Looking at the box, I was a little surprised to read this on the box:

"The less you use the solar panel to recharge the battery, the longer the battery will last"

Looking online I found:"RoamProofs product's battery life will decrease when the solar panel is used to recharge the device's battery. Extend the life of any internal battery by charging through a wall adapter using provided charging cables."